Bach 5C vs Kelly 5C-BUGLE
The Kelly 5C-BUGLE has a wider cup diameter, the Kelly 5C-BUGLE features a deeper cup, the Kelly 5C-BUGLE has a larger throat opening.
Cup Diameter
The Kelly 5C-BUGLE has a cup diameter of 16.76 mm / 0.6598 in compared to 16.25 mm / 0.6398 in on the Bach 5C — a difference of 0.51 mm / 0.0201 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Kelly 5C-BUGLE has a very deep cup while the Bach 5C has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Kelly 5C-BUGLE has a wider throat (3.80 mm / 0.1496 in vs 3.66 mm / 0.1441 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Material
The Bach 5C is described as unspecified, and the Kelly 5C-BUGLE as Lexan polycarbonate. Material affects mass, warmth, and how quickly the piece responds.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.